Securities Law Commons^™

Power And Statistical Significance In Securities Fraud Litigation, Jill E. Fisch, Jonah B. Gelbach

All Faculty Scholarship

Event studies, a half-century-old approach to measuring the effect of events on stock prices, are now ubiquitous in securities fraud litigation. In determining whether the event study demonstrates a price effect, expert witnesses typically base their conclusion on whether the results are statistically significant at the 95% confidence level, a threshold that is drawn from the academic literature. As a positive matter, this represents a disconnect with legal standards of proof. As a normative matter, it may reduce enforcement of fraud claims because litigation event studies typically involve quite low statistical power even for large-scale frauds.

This paper, written for …

Federal Securities Fraud Litigation As A Lawmaking Partnership, Jill E. Fisch

All Faculty Scholarship

In its most recent Halliburton II decision, the Supreme Court rejected an effort to overrule its prior decision in Basic Inc. v. Levinson. The Court reasoned that adherence to Basic was warranted by principles of stare decisis that operate with “special force” in the context of statutory interpretation. This Article offers an alternative justification for adhering to Basic—the collaboration between the Court and Congress that has led to the development of the private class action for federal securities fraud. The Article characterizes this collaboration as a lawmaking partnership and argues that such a partnership offers distinctive lawmaking advantages. …